Presidents routinely come in promising to rise above the warfare, and fail. A national political expert lists all the factors that have produced the demolition derby of national politics.

Watching the political conventions pulls me in two directions. Do I believe the occasional fine talk about transcending differences to solve our big problems in a lasting (namely, bipartisan) way? Or do all the partisan rancor and demonizing foretell “four more years” of impasses? I fear it’s the latter, with a little soothing aloe about cooperation to gull the independents every four years.

One reason for my pessimism was a talk I heard recently by Ronald Brownstein, a distinguished political analyst who was in Seattle to address supporters of the William D. Ruckelshaus Center, an institute at the University of Washington and Washington State University that facilitates collaborative problem solving. The Center has been studying civil public discourse, as a fundamental aspect of problem solving. Brownstein was in town to provide some analysis and perspectives. It was very sobering.

Brownstein’s history lesson began by recalling the “ramshackle assemblages” that used to characterize Congress and national parties, and which allowed for temporary coalitions to pass important bills. Each party had conservative and progressive wings, so deal making across the aisles was always an option.

In the period 1938-88, Brownstein argues, we had in effect “four-party politics,” with the four parties made up of Southern Democrats, Moderate-to-Liberal Democrats, Liberal Republicans, and Old Guard Republicans. This system arose after FDR failed to pack the Supreme Court and he realized that even his strong majorities in Congress couldn’t pass major legislation and make it stick without help from other parts of the four parties. LBJ was the last great master of it, with Bill Clinton adept at it but defeated by the Gingrich revolt in Congress.

Probably the last major bipartisan deal was George H.W. Bush’s 1990 budget deal, raising taxes. Since then, it’s been permanent polarization, with much less diversity in either party (the Democrats have more), straight party-line voting, supermajority requirement that give a minority party veto-rights, and what few big measures pass usually have no votes from the other party and therefore little staying power politically.

In effect, Brownstein argues, we have drifted into a "quasi-parliamentary system," where members are required to stand with their parties, not vote their consciences or their districts, where the party leadership imposes solutions on the members, and you have a governing party (normally a slender majority) and an opposition party whose role is to oppose and sabotage, not negotiate and seek common ground. Of course, our presidential system is not set up to work this way. It is made worse when, in the Senate, even a normal majority does not give control, owing to the filibuster.

Newt Gingrich, in his take-no-prisoners insurgency in 1994, consciously installed this kind of lock-step system, but there are many other factors contributing to the continuous warfare of current politics. One factor is the rise of overtly partisan media, which provide a loud megaphone for censuring independent-minded politicians who wander from the party line, and which frame issues in stark terms. Activist groups on the edges of the parties are now able to intimidate dissidents by raising lots of national money to challenge such strays in primaries, punishing compromisers and driving them from the party. The Internet greatly facilitates the raising of such national, movement money.

Another factor is the demise of the old seniority system in the Congress, by which long-serving members from safe seats (often in the South) rose to committee chairmanships and paid little heed to party leadership, since they were impregnable. That ended in the 1974 reforms, giving the party caucuses the right to elect chairs and sending a strong signal that party loyalty was now the path to a chairmanship.

A last factor is what has been called “the great sort” of the electorate, by which all the liberals defected from the Republican Party, where they were a significant factor (remember Gov. Dan Evans and Gov. Tom McCall?), to the Democrats; and conservatives migrated in large numbers from the Democratic party. Seattle, with not a single Republican in the Legislature is an example of this sorting out, and it’s one reason why the state GOP can treat Seattle issues as if they are toxic: they don’t have to worry about protecting some urban Republicans.

There used to be resistance to this at the local level, and governors tended to be much more pragmatic. Even that is changing, Brownstein contends, and the pressure to conform (or face the consequences of meager national campaign contributions) makes governors behave much more like U.S. senators. Thus we see Rob McKenna feeling the need to join the national Republican opposition to Obama’s health care plan, and Jay Inslee toeing the national teachers’ union lines in exchange for buckets of national money and imported help in managing his floundering campaign.

As long as neither party faces obliteration at the ballot box, they can continue migrating to the hot-button extremes, where the money is, the ardent activists reside, and the media prowl for quotes. It's a fatal situation. The country remains closely divided, which means all the big issues like the deficit or global climate change end up in noisy stalemates or various postponement devices like sequestration.

Brownstein thinks the Republicans are the more extreme examples of this, having purged all their moderates. Furthermore, they are in danger of becoming a white party. Romney’s strategy relies on his getting a very high (61 percent) proportion of the white vote, just as Obama is hoping for 80 percent of the minority vote. That racial polarization is dangerous. It also puts the GOP out of step with the changing demographics of the country, now 37 percent non-white. Some other figures, from the 2010 census: Americans under age 18 are 47 percent non-white; 49 percent of schoolchildren are non-white, and 26 percent of the vote comes from minorities.

Or take Mecklenburg County, home county of Charlotte, N.C., where the Democratic convention is being held. The Hispanic population has risen from 6,000 in 1990 to 111,000 today, with 830,000 in the state (keep in mind only about one fifth of Hispanics can vote).

George W. Bush, who got 40 percent of the Hispanic vote in 2004, definitely pushed for Republican inroads to this rising minority group. Hispanics should be open to Republican positions. Hispanics have high marriage and church-going percentages, lots of entrepreneurs, and are socially conservative Catholics, opposing abortion. Polling shows 40 percent of Hispanics describe themselves as “conservative.” Yet Romney and the new Republican party are pushing away Hispanic support by blocking immigration reform, clamping down on undocumented workers, and squeezing education funding. Romney has been getting only about 26 percent Latino support in polls, though that has risen a bit lately.

If Romney does manage to win, Brownstein feels, it may be the last hurrah for the GOP's squeezing out such a lily-white victory. Long-term, this racial divide is ominous, and probably unsustainable. Brownstein explained in a recent column in National Journal:

For Republicans, that prospect crystallizes the danger of an electoral strategy that has left the party almost entirely dependent on white voters, even as their numbers decline. For Democrats, the possibility that President Obama could face landslide rejection from the white majority, even if he survives, underscores the party’s inability to hold support among whites while implementing its agenda, a trend that traces back to Lyndon B. Johnson.

Is there any way out of these destructive patterns? Brownstein notes that there were two previous times in American history when we had such high instances of party-line voting and hyperpartisanship. One was the period leading up to the Civil War. The other was 1890-1908, when the Gilded Age was starting to crack apart under attacks from Populists and Progressives. Teddy Roosevelt, by bolting from the Republican party in 1912 and handing the election to Woodrow Wilson, broke up that standoff.

What could do it this time? Pressure from voters and public-good organizations? A third party that, like T.R.’s Bull Moose Party doesn’t actually win but shakes apart a fatal system? The defection of the business community from going along with a reactionary political party, even with its selfish rewards in deregulation and low taxes, and demanding some stability and maturity? Growing numbers of states that ignore the national demolition derbies and just work things out at the local level? A president with the courage to lay out some grand compromises and dares the other side to torpedo them?

Most likely: a financial crisis so bad that voters decide to stop enjoying the circus, sober up, and force the politicians to face the music of this devil's waltz.